Hey there,
Well, i'm currently doing a personal project using Maya 3.0. I've experienced no trouble editing my polygon UV map up until now... but have recently discovered that if i move UV points in the map (in Texture View), everything "looks" okay, until i save/reload... in which case they are back to where they were. When i try rendering, there's no change either. Also, if i move the UV points (and visually it 'looks' like i've succeeded), and then run the tExtractor plugin to get a image of the new UV map... the image shows the unaltered UV map... it's like i never touched the thing. I don't know how, but somehow i must've "locked" the UV map into it's current shape. It seems like i can edit it, but it turns out to only be an illusion.
I hope someone out there might have the answer i'm looking for... 
Thanks,
AnimbBoy